Turbomachine with integral generator/starter

ABSTRACT

A turbomachine such as an aircraft turbojet including an electrical generator/starter that can be mounted and dismounted by axial translation in an upstream enclosure of the turbomachine between the low-pressure compressor and the high-pressure compressor, and couple to electrical cables which extend inside the structural arms of the intermediate casing of the turbomachine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional Application of, and claims the benefitof priority under 35 U.S.C. § 120 from, U.S. application Ser. No.11/626,649, filed Jan. 24, 2007, herein incorporated by reference, whichclaims the benefit of priority under 35 U. S.C. § 119 from French PatentApplication No. FR 06 00617 filed Jan. 24, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a turbomachine, such as an aircraft turbopropor turbojet, equipped with an electrical generator forming a startermounted axially in the turbomachine, and it also relates to agenerator/starter for a turbomachine of this type.

2. Discussion of the Background

In document EP-A-1 382 802 there is already proposed a turbomachineequipped with an integral generator/starter in which thegenerator/starter is mounted in the bore of one or two moving-bladediscs of the compressor of the turbomachine.

SUMMARY OF THE INVENTION

The present invention is aimed in particular at improving this type ofturbomachine by facilitating the mounting and dismounting of theintegral generator/starter, in particular for maintenance purposes, andby simplifying its connections to electrical current supply or currentdistribution cables.

To this end it proposes a turbomachine comprising an electricalgenerator/starter whose rotor is driven by the shaft of a high-pressurecompressor and whose stator is carried by an intermediate casing of theturbomachine, the generator/starter being disposed in an upstreamenclosure of the turbomachine situated inside the intermediate casingbetween the low-pressure compressor and the high-pressure compressor,and comprises means of coupling to electrical cables extending insidestructural arms of the intermediate casing.

The arrangement, according to the invention, of the generator/starter inthe upstream enclosure of the turbomachine, between the low-pressurecompressor and the high-pressure compressor, makes it possible to mountand dismount the generator/starter by axial translation from theupstream part of the turbomachine, thereby facilitating the maintenanceoperations and reducing their duration.

Moreover, this arrangement makes it possible to pass the electricalcables couple to the generator/starter along the inside of thestructural arms of the intermediate casing, these cables being rigid andof relatively large cross section.

As this upstream enclosure of the turbomachine contains oil, thegenerator/starter accommodated in this enclosure is encased in aleaktight housing.

To facilitate the electrical connections of the generator/starter to thecurrent supply/distribution cables, this leaktight housing is surroundedby a chamber delimited by the intermediate casing and by the housing andsupplied with compressed air, this compressed air being able to enterthe leaktight housing through inlet orifices made therein so as toestablish in the housing an air overpressure opposing the entry of oil.

The leaktight housing furthermore comprises first means of coupling tothe electrical cables passing along the inside of the arms of theintermediate casing, these first means of coupling passing leaktightlythrough a wall of the housing and extending inside the chamber suppliedwith compressed air.

These first means of coupling are couple outside the housing to secondmeans of coupling which form a leaktight feedthrough through a wall ofthe chamber supplied with compressed air and which extend outside thischamber.

The couples between the first means of coupling carried by the leaktighthousing and the second means of coupling are thus situated in thechamber supplied with compressed air and are protected from the oilcontained in the upstream enclosure of the turbomachine.

Advantageously, the first means of coupling extend inside this chamberparallel to the axis of the rotor and are pushed onto the second meansof coupling.

For example, the first means of coupling comprise, outside the housing,an axial female portion that can be pushed onto an axial male portion ofthe second means of coupling.

This allows blind mounting of generator/starter in the turbomachine, theelectrical connections being effected automatically in the course ofthis mounting.

In a preferred embodiment of the invention, the leaktight housing of thegenerator/starter comprises an external cylindrical element forming asupport of the stator of the generator/starter and carrying the firstmeans of coupling, an internal cylindrical element forming the supportof the rotor of the generator/starter, and upstream and downstreamannular hoods fixed to the external cylindrical element at its ends andcooperating leaktightly with the internal cylindrical element by way ofrotating seals.

The generator/starter according to the invention and its leaktighthousing have a modular structure facilitating their mounting and theirdismounting and making it possible moreover, for maintenance operations,to remove from the upstream enclosure the internal cylindrical elementcarrying the rotor of the generator/starter while leaving in place theexternal cylindrical element carrying the stator of thegenerator/starter.

The invention also proposes a generator/starter of the type describedhereinabove for a turbomachine, this generator/starter being one whichcomprises a leaktight housing consisting of: an external cylindricalelement forming a stator support; an internal cylindrical elementcoaxial with the external cylindrical element forming a rotor support;and annular hoods fixed to the axial ends of the external cylindricalelement and cooperating with the internal cylindrical element viarotating seals.

Bent means of coupling to electrical cables are carried by the externalcylindrical element of the housing and emerge axially outside thelatter.

The external cylindrical element of the housing comprises an annularshell for fixing to an intermediate casing of the turbomachine, and theinternal cylindrical element of this housing comprises an annular flangefor fixing to a rotational drive shaft.

In this generator/starter, the internal cylindrical element comprisesmeans of support for permanent magnets and the external cylindricalelement comprises means of support for coils.

These two cylindrical elements are provided with channels forcirculation of cooling oil.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and other characteristics,details and advantages thereof will become more clearly apparent onreading the description which follows, given by way of example withreference to the appended drawings in which:

FIG. 1 is a partial diagrammatic half-view in axial section of aturbomachine according to the invention;

FIG. 2 is a diagrammatic half-view in axial section, on a larger scale,of the generator/starter mounted in the upstream enclosure of theturbomachine;

FIG. 3 is an enlarged view illustrating means of electrical coupling ofthis generator/starter;

FIG. 4 represents these means of coupling in the unplugged state;

FIG. 5 diagrammatically represents means of electrical connection of thegenerator/starter to electronic power circuits;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Represented diagrammatically in FIG. 1 is an intermediate casing 10 of aturbomachine such as a turbofan, this intermediate casing being locatedbetween a low-pressure compressor situated upstream and associated witha fan, and a high-pressure compressor situated downstream and supplyinga combustion chamber of the turbomachine.

The intermediate casing 10 comprises structural arms 12 which extendradially through the primary stream 14 and through the secondary stream16 and whose external ends support the fan nacelle of the turbomachine.

The intermediate casing 10 delimits internally an upstream enclosure 18in which are accommodated the upstream end of the shaft 20 of thehigh-pressure compressor and a bearing 22 for guiding this shaft, theenclosure 18 being traversed axially by the shaft 24 of the turbine,whose upstream part constitutes the drive shaft of the low-pressurecompressor of the turbomachine.

An electrical generator 26 that can also operate as a starter isaccommodated in a leaktight housing 28 inside the enclosure 18 andcomprises a rotor 30 driven by the shaft 20 of the high-pressurecompressor and a stator 32 carried by the intermediate casing 10, therotor 30 comprising permanent magnets which rotate inside electricalcoils forming part of the stator 32.

These coils are couple to electrical conductors 34 for distributingcurrent (when operating as a generator) and for supplying current (whenoperating as a starter) and which are accommodated in the structuralarms 12 of the intermediate casing 10. These conductors couple thegenerator/starter 26 to electronic power circuits 36 mounted inside thenacelle of the fan, downstream of the intermediate casing 10.

The electrical conductors 34 are rigid cables of relatively sizeablecross section (for example around 50 mm²) which it is very difficult orimpossible to curve and which follow rectilinear paths in the structuralarms 12 of the intermediate casing. These conductors 34 are couple tothe generator/starter 26 and to the electronic circuit 36 by way of bentmeans of coupling, comprising first means of coupling 38 carried by theleaktight housing 28 of the generator/starter 26, second means ofcoupling 40 carried by an annular wall 42 of the intermediate casingdelimiting internally the core of the primary stream 14 and surroundingexternally the upstream enclosure 18, and third means of coupling 44carried by the external ends of the structural arms 12.

In an exemplary embodiment, three sets of first, second and third meansof coupling, 38, 40 and 44, are provided for coupling thegenerator/starter 26 to the electronic circuits 36, these three setsbeing distributed at 90° to one another about the axis A of theturbomachine, and the third means 44 of coupling each being couple byconductors 34 of the aforesaid type to the electronic power circuits 36.

As may be seen better in FIG. 2, the housing 28 of the generator/starter26 comprises an internal cylindrical element 46 which carries thepermanent magnets constituting the rotor 30 of the generator/starter andwhich is mounted in axial translation on a support shaft 48 carried bythe upstream end of the shaft 20 of the high-pressure compressor, thehousing 28 also comprising an external cylindrical element 50, coaxialwith the internal cylindrical element 46 and carrying the stator 32 ofthe generator/starter, and upstream 52 and downstream 54 annular hoodswhich are fixed to the axial ends of the external cylindrical element 50and which cooperate leaktightly via rotating seals 56 with the axialends of the internal cylindrical element 46.

The upstream end of the internal cylindrical element 46 comprises aninternal annular flange 58 for fixing, by means of screws, to thesupport shaft 48 secured to the shaft 20 of the high-pressurecompressor. The upstream annular hood 52 is fixed by screws accessiblefrom upstream to the upstream end of the external cylindrical element 50of the housing 28.

Channels 60 for circulating cooling oil are formed in the externalelement 50 and supplied with oil at their upstream end by a duct coupledto an oil feed pipe passing into the enclosure 18. At their downstreamend, these channels 60 are linked to the lubrication circuit of theupstream bearing 22 for guiding the shaft 20.

Channels 66 for circulating cooling oil are also formed in the internalcylindrical element 46 and emerge at their downstream end into theenclosure 18, on the bearing 22 side.

The external cylindrical element 50 of the housing 28 comprises anexternal annular shell 68 for fixing by means of screws to the annularwall 42 of the intermediate casing 10, this annular shell delimitingabout the external cylindrical element 50 a chamber 70 closed on thedownstream side by an annular shell 72 dependent on the annular wall 42of the intermediate casing, this annular shell 72 being terminated atits internal periphery by a cylindrical span in which the downstream endof the internal cylindrical element 50 of the housing 28 is leaktightlyengaged.

The chamber 70 which surrounds the external cylindrical element 50 issupplied with compressed air from the primary stream 14 by orifices ofthe annular wall 42 which emerge into the chamber 70. Passages formed inthe external cylindrical element 50 emerge inside the housing 28 andfeed the compressed air inside this housing around the generator/starter26 to prevent any entry of oil into the housing 28 from the upstreamenclosure 18 of the turbomachine.

As may be seen better in FIGS. 3 and 4, the first means 38 of couplingcarried by the leaktight housing 28 and the second means 40 of couplingcarried by the annular wall 42 of the intermediate casing, emerge intothe chamber 70 in such a way as to avoid any pollution of the electricalconnections between these means of coupling by the oil contained in theenclosure 18.

More precisely, the first means of coupling 38 comprise a 90° bent duct74, secured to the external cylindrical element 50 of the housing 28,this bent duct 74 emerging inside the housing 28 via its radiallyinternal end and being closed at its radially external end by aconnector 76 forming a female portion fixed by screws to the externalend of the duct 74.

In the example represented, the connector 76 comprises a base made ofdielectric material, in which are mounted three tubular conductors 78which, at their upstream end, receive three conductors 80 linked to thecoils of the stator of the generator/starter and which, at theirdownstream end, are intended to receive pins 82 mounted in a base 84made of dielectric material of a male connector 86 forming part of thesecond means 40 of coupling.

The conductors 78 of the female portion of the first means of coupling38 extend parallel to the axis of the generator/starter 26, as well asthe pins 82 of the male portion of the second means of coupling, and arealigned axially with these pins. The base 84 of the male portion of thesecond means of coupling 40 is dimensioned so as to fit leaktightly intothe female base 76 of the first means of coupling 38. Thus, when theexternal cylindrical element 50 carrying the first means of coupling 38is put in place by axial translation from upstream to downstream, thefemale base 76 engages directly on the male base 84 and the connectors76 and 86 are automatically coupled to one another, the pins 82 beingengaged in the tubular conductors 78 of the connector 76.

Conversely, on dismounting the generator/starter 26, the axialtranslation from downstream to upstream of the external cylindricalelement 50 is converted automatically into the separation of theconnectors 76 and 84, as represented in FIG. 4.

The second means of coupling 40 are carried by the annular wall 42 ofthe intermediate casing 10 and pass leaktightly through this wall. Theyconsist essentially of the male connector 86 described previously whichextends from the wall 42 inside the chamber 70 and of a female connector76 identical to that of the first means of coupling 38 and which extendsoutside the annular wall 42 in the core of the primary stream 14. Thetwo connectors 86 and 76 of the second means of coupling 40 are joinedby their external annular flanges which are fixed by screws to theannular wall 42 of the intermediate casing from the chamber 70.

The tubular conductors 78 of the connector 76 of the second means ofcoupling 40 receive rigid conductors 88, three in number, which areaccommodated in a screening sheath 90 and which extend radially outwardinside the arm 12 of the intermediate casing.

At their radially external end, these conductors 88 are linked (FIG. 5)by the third means of coupling 44 and conductors 34 to the electronicpower circuits 36 represented in FIG. 1.

The third means of coupling 44 comprise a 90° bent duct 92 at the endsof which are mounted female connectors 76 of the type describedpreviously, linked together inside the duct 92 by conductors 94.

For the mounting of the generator/starter, the following is carried out:

-   the shaft 48 supporting the rotor of the generator/starter is first    of all put in place and mounted on the shaft of the high-pressure    compressor of the turbomachine,-   next, the external cylindrical element 50 equipped with the    downstream hood 54 is put in place by axial translation from    upstream to downstream, and is fixed to the intermediate casing by    its external annular shell 68. The electrical connection between the    first and the second means of coupling 38, 40 is done automatically,    as is the connecting of the oil supply of the bearing 22,-   the connecting of the means of oil supply of the channels 60 of the    external cylindrical element 50 is carried out next,-   next, the internal cylindrical element 46 carrying the rotor 30 of    the generator/starter is put in place by axial translation from    upstream to downstream and its annular flange 58 is fixed by screws    or bolts to the support shaft 48,-   next the upstream hood 52 is put in place and it is fixed by means    of screws to the external cylindrical element 50.

The generator/starter according to the invention has a certain number ofadvantages:

-   its modular structure facilitates its mounting and its dismounting    in the turbomachine,-   the stator of the generator/starter, carried by the external    cylindrical element 50, can remain fixed to the intermediate casing    when dismounting the shaft of the high-pressure compressor during    maintenance operations,-   the means of electrical coupling of the generator/starter are    located in a compressed air enclosure outside the upstream enclosure    18 of the turbomachine,-   the electrical connection cables 34 are protected inside structural    arms 12 of the intermediate casing,-   the means of coupling 38, 40, 42 are preassembled and leaktight and    allow the use of screened, rigid and straight conductors or cables,    that do not need to be bent,-   the electrical connections between the first and the second means of    coupling 38, 40 are done blind in a safe manner by axial    translation.

1. A generator/starter for a turbomachine comprising: a stator; a rotorrotatable with respect to said stator; an annular housing enclosing saidstator and said rotor and including an external cylindrical elementdefining an external surface of said annular housing and forming asupport for said stator; an internal cylindrical element defining aninternal surface of said annular housing, coaxial with the annularexternal cylindrical element and forming a support for said rotor, saidinternal cylindrical element being rotatable with respect to saidexternal cylindrical element; and annular hoods fixed to axial ends ofthe external cylindrical element and cooperating with the internalcylindrical element via rotating seals; wherein bent means of couplingcoils of the stator to electrical cables are carried by the annularexternal cylindrical element of the annular housing and emerge axiallyoutside the annular housing.
 2. The generator/starter as claimed inclaim 1, wherein the external cylindrical element of the annular housingcomprises an annular shell for fixing to an intermediate casing of theturbomachine.
 3. The generator/starter as claimed in claim 1, whereinthe internal cylindrical element comprises an annular flange for fixingto a rotational drive shaft.
 4. The generator/starter as claimed inclaim 1, wherein the internal cylindrical element comprises means ofsupport for permanent magnets forming the rotor of the generator/starterand the external cylindrical element comprises means of support forcoils forming the stator of the generator/starter.
 5. Thegenerator/starter as claimed in claim 1, wherein the internal andexternal cylindrical elements of the annular housing comprise channelsfor circulation of cooling oil.